Enhancing mechanical properties of dredged sludge through carbonation stabilization employing steel slag: An eco-friendly and cost-effective approach

Carbonation stabilization presents an efficacious and eco-friendly soil stabilization method with extensive applicability. Because market costs play a crucial role in determining the recycling of dredged sludge, this research investigates the potential use of solid waste steel slag as a cost-effective alternative stabilizing agent. The objective is to promote the wider adoption of carbonation stabilization technology for the reuse of dredged sludge. This investigation examined the alteration patterns of unconfined compressive strength and CO2 uptake in steel slag carbonation stabilized soils (CS) under varying steel slag contents, stabilization moisture contents, and carbonation durations. Furthermore, a detailed analysis of micro-mineral composition and micro-pore structure evolution during the carbonation process was conducted employing X-ray diffraction (XRD), thermogravimetric and derivative thermogravimetric analysis (TG-DTG), and mercury intrusion porosimetry (MIP). The outcomes revealed a positive linear association between the unconfined compressive strength of CS specimens and their CO2 uptake across different steel slag contents and carbonation durations. Through XRD and TG-DTG assessments, the carbonation byproducts in CS specimens were identified as calcite-type CaCO3, with an increasing concentration of CaCO3 correlating with the increase of steel slag content and carbonation duration. MIP testing revealed that a 72-hour carbonation period could diminish the total porosity of steel slag dredged soils from 40.96% to 34.53%. The strength of CS specimens predominantly derives from the carbonation reaction of steel slag, which enhances the soil's mechanical attributes through the cementing and pore-filling impacts of CaCO3 crystal growth on the soil matrix.